1. Field of the Invention
The present invention relates generally to sheet film cassettes for photographic cameras and more particularly to such a cassette which ensures proper loading of a sheet film.
2. Discussion of the Related Art
A standard sheet film cassette is described in West German patent No. 827,749. The described cassette can be loaded and unloaded conveniently from the rear of the cassette when the rear wall is open. In addition, the position of a loaded sheet film is determined by supporting shoulders located on the periphery of the picture defining gate so that in theory the light-sensitive layer of the sheet film is always in the same plane independent of the thickness of the carrier material. This film plane is nearly parallel with the ground-glass plane of the camera. Despite these theoretical advantages, practical application of the described sheet film cassette has proven that the loaded sheet film is frequently not completely parallel but rather is arched away from the pressure plate against the front side of the cassette between the opposing supporting shoulders. Such arching impairs optimal sharpness of the photograph.
Accordingly, it is an object of the present invention to improve the sharpness of photographs while providing convenient loading and unloading of the film.
It is a further object of the present invention to design a sheet film cassette of the aforementioned kind such that the loaded sheet film is always forced to lie snugly against the pressure plate, thereby guaranteeing that the light-sensitive layer of sheet film to be exposed lies almost entirely flat in the plane defined by the supporting shoulders.
Another object of the present invention to obtain the foregoing objects regardless of the thickness of the carrier material.
Other objects and advantages are apparent in the drawings and description which follow.